Aramid fiber impregnation liquid, aramid fiber impregnation line and preparation method

Abstract

The invention relates to the technical field of fiber impregnation, in particular to an aramid fiber impregnation liquid, an aramid fiber impregnation thread and a preparation method, and the aramid fiber impregnation liquid comprises a first-bath impregnation liquid and a second-bath impregnation liquid; the one-bath impregnation liquid is prepared from the following components in parts by weight: 34 to 40 parts of anhydride-polyol copolymer, 17 to 20 parts of trimethylolpropane polyvinyl ether, 12 to 15 parts of amino silane coupling agent, 0.001 to 0.01 part of glacial acetic acid and 320 to 330 parts of deionized water; the two-bath impregnation liquid comprises 10-30 parts of epoxy resin, 2-5 parts of a solubilizer, 3-9 parts of a natural polyphenol compound, 4-9 parts of an amine curing agent, 5-12 parts of an anti-damp-heat aging aid, 180-250 parts of deionized water and 100-160 parts of rubber latex. The impregnation liquid is more environment-friendly, and the aramid fiber impregnated threads have the advantages of being good in adhesive force with hydrogenated nitrile rubber, green, environmentally friendly, resistant to damp-heat aging and the like.

Description

Technical Field

[0001] This invention relates to an aramid impregnation solution, an aramid impregnation thread, and a preparation method thereof, belonging to the field of fiber impregnation technology. Background Technology

[0002] The service environment of critical components such as fuel lines for aero-engines and high-end hydraulic pipelines is characterized by high temperature, high pressure, and severe vibration, placing stringent requirements on the lightweight, high strength, and structural stability of materials. Para-aramid, as a high-performance synthetic fiber, has a density of only 1.44 g / cm³. 3 With tensile strengths reaching 2.8~3.5 GPa and elastic moduli as high as 70~110 GPa, coupled with excellent fatigue resistance and dimensional stability, it has become an ideal candidate material for reinforcing rubber-based composites. Hydrogenated nitrile butadiene rubber (NBR) is widely used in high-temperature oil media service scenarios such as fuel lines for aero-engines due to its excellent oil resistance, temperature resistance, and mechanical stability. Reinforcing it with para-aramid fibers can further improve its tensile strength, tear resistance, and creep resistance, meeting the high-performance requirements of key components.

[0003] Para-aramid fibers exhibit a highly ordered and rigid molecular chain, with molecules tightly bound together by strong hydrogen bonds, resulting in a smooth fiber surface and a lack of active groups. When compounded with hydrogenated nitrile rubber, this surface characteristic makes it difficult for the fiber and rubber matrix to form effective chemical bonding and physical adsorption, leading to weak interfacial adhesion and severely impacting the overall mechanical properties and service reliability of the composite material. Therefore, it is necessary to modify para-aramid fibers through surface impregnation treatment to introduce active functional groups and improve surface roughness. However, the formaldehyde contained in the traditional RFL impregnation system is highly toxic and carcinogenic, and resorcinol also has certain biotoxicity. These substances pose hazards to the environment and the health of operators during production, use, and waste disposal, which is inconsistent with current environmental regulations and the development trend of green manufacturing. In addition to the RFL system, some alternative impregnation systems use organic solvents such as toluene and xylene as dispersion media. Although these can improve the interfacial adhesion to some extent, these organic solvents are highly volatile, flammable, and explosive, making it difficult to meet the environmental protection requirements for industrial applications. Therefore, developing non-toxic and environmentally friendly water-soluble impregnation systems has become an important direction for solving the environmental problems of traditional impregnation systems.

[0004] While hydrogenated nitrile butadiene rubber (HNBR) exhibits excellent oil resistance, its polar groups in its molecular structure result in poor water resistance, making it prone to absorbing moisture in humid environments or during service. When para-aramid / HNBR composites are used in applications such as fuel lines in aero-engines, although they primarily come into contact with oil media, moisture and condensation in the service environment can still penetrate through the rubber matrix to the fiber / rubber interface, invading the interior of the para-aramid fibers. This moisture penetration causes two serious problems: firstly, the formation of a water film at the interface disrupts the existing chemical bond and physical adsorption between the fiber and rubber, leading to a significant decrease in interfacial adhesion; secondly, the amide bonds in the para-aramid fibers are prone to hydrolysis under humid and hot conditions, causing fiber molecular chain breakage, reduced crystallinity, and degradation of the fiber's mechanical properties, thus affecting the reinforcing effect of the composite material. This humid and hot aging damage accumulates over service time, eventually leading to delamination, cracking, and other failure phenomena in the composite material. Therefore, while developing water-soluble and environmentally friendly impregnation systems, it is also necessary to take into account the system's resistance to humid heat aging. Impregnation modification should not only improve the initial interfacial adhesion, but also build an effective moisture barrier to inhibit moisture penetration, delay the humid heat aging process of the interface and fibers, and ensure that the composite material maintains a stable reinforcing effect and structural reliability during long-term service. Summary of the Invention

[0005] This invention addresses the problems of existing para-aramid impregnation systems, such as insufficient environmental friendliness, poor adhesion to hydrogenated nitrile butadiene rubber, and poor resistance to damp heat aging after being compounded with hydrogenated nitrile butadiene rubber. It provides an aramid impregnation solution, an aramid impregnation line, and a preparation method. The impregnation solution is more environmentally friendly, and the aramid impregnation line has advantages such as good adhesion to hydrogenated nitrile butadiene rubber, green environmental protection, and resistance to damp heat aging.

[0006] The technical solution of the present invention to solve the above-mentioned technical problems is as follows: an aramid impregnation solution, wherein the aramid impregnation solution comprises a one-bath impregnation solution and a two-bath impregnation solution; The one-bath impregnation solution comprises, by weight, 34-40 parts of anhydride-polyol copolymer, 17-20 parts of trimethylolpropane polyethylene ether, 12-15 parts of aminosilane coupling agent, 0.001-0.01 parts of glacial acetic acid, and 320-330 parts of deionized water. The two-bath impregnation solution comprises, by weight, 10-30 parts epoxy resin, 2-5 parts solubilizer, 3-9 parts natural polyphenol compound, 4-9 parts amine curing agent, 5-12 parts anti-damp heat aging agent, 180-250 parts deionized water, and 100-160 parts rubber latex.

[0007] Furthermore, the anhydride-polyol copolymer is at least one of maleic anhydride-glycerol copolymer, maleic anhydride-pentaerythritol copolymer, and maleic anhydride-neopentyl glycol copolymer; The aminosilane coupling agent is at least one of KH792, KH540, and KH550.

[0008] Further, the epoxy resin is at least one of glycerol triglycidyl ether, neopentyl glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, bisphenol A type epoxy resin, and bisphenol S type epoxy resin.

[0009] Furthermore, the solubilizer is at least one of polyoxyethylene castor oil EL-40, propylene glycol methyl ether, and polyethylene glycol monomethyl ether; The natural polyphenolic compound is at least one of ellagitannin, gallic acid, ethyl gallate, and tannic acid; The amine curing agent is at least one of triethylenetetramine, dipropylenetriamine, cyclohexanetriamine, m-phenylenetriamine, isophorone-derived triamine, phenylcyclotriamine, and cyclohexanetetramine.

[0010] Furthermore, the anti-damp heat aging aid is selected from at least one of microencapsulated bisphenol A diglycidyl ether, rutile nano TiO2 powder, and nano SiO2 powder; and the anti-damp heat aging aid includes at least microencapsulated bisphenol A diglycidyl ether.

[0011] Furthermore, the rubber latex includes butadiene-pyridine latex and carboxylated butadiene-acrylonitrile latex, and the mass ratio of butadiene-pyridine latex to carboxylated butadiene-acrylonitrile latex is (3-7):1.

[0012] Furthermore, the preparation method of the two-bath impregnation solution is as follows: According to the weight proportions, take 30-50 parts of deionized water, 10-30 parts of epoxy resin, 2-5 parts of solubilizer and 3-9 parts of natural polyphenol compound, stir and mix them, and then react them under stirring conditions at 40-80℃ to obtain intermediate products. The intermediate product is mixed with 4-9 parts of amine curing agent, 5-12 parts of anti-damp heat aging agent, 150-200 parts of deionized water and 100-160 parts of rubber latex, and then cured to obtain a two-bath impregnation solution.

[0013] This invention also discloses a method for preparing aramid impregnated yarn, the method comprising: S1. After the twisted para-aramid fibers are immersed in a one-bath impregnation solution, they are dehydrated, dried, and heat-treated. S2. The para-aramid fiber treated in step S1 is impregnated in a second bath impregnation solution, and then dried and heat-treated to obtain aramid impregnated yarn. The one-bath impregnation solution is the one-bath impregnation solution of the present invention; The two-bath impregnation solution is the two-bath impregnation solution described in this invention.

[0014] Further, in step S1, the twisted para-aramid fibers are impregnated in a one-bath impregnation solution at a traction speed of 2~8 m / min for 30~80 s, then dried at 100~130 ℃ for 60~120 s, and finally drawn to a heat treatment system for heat treatment at 170~210 ℃ for 60~120 s. In step S2, the twisted para-aramid fibers are impregnated in a second bath impregnation solution at a traction speed of 2-8 m / min for 30-80 s, then dried at 100-130 ℃ for 60-120 s, and finally drawn into a heat treatment system for heat treatment at 210-230 ℃ for 60-150 s to obtain aramid impregnated yarn.

[0015] The present invention also discloses an aramid impregnated yarn, which is prepared by the preparation method described in the present invention.

[0016] The beneficial effects of this invention are: Compared to the traditional RFL impregnation system, the aramid impregnation solution of this invention does not contain highly toxic resorcinol and formaldehyde, and can achieve good bonding effect between para-aramid and hydrogenated nitrile rubber in a more environmentally friendly way. Furthermore, the water solubility of epoxy resin is improved by using solubilizers and natural polyphenol compounds. This not only further enhances the bonding effect by introducing active groups such as hydroxyl groups, but also avoids the use of organic solvents such as toluene, making it more green, environmentally friendly and safe.

[0017] In the one-bath impregnation solution of this invention, the aminosilane coupling agent molecule has a hydrophilic amino terminus and a hydrophobic siloxane terminus, providing a bridge for the subsequent bonding of aramid fibers with the organic phase. The anhydride-polyol copolymer introduces polar functional groups such as carboxyl groups, ester groups, and hydroxyl groups on the aramid surface for activation, constructing a basic film-forming layer and improving the adhesion of the impregnation solution. Trimethylolpropane polyethylene ether, as a nonionic polyether additive, can reduce the surface tension of the impregnation solution and improve the wettability of the aramid. In the two-bath impregnation solution, the abundant epoxy groups in the epoxy resin can undergo a ring-opening reaction with the amino groups in the amine curing agent to generate a cross-linked and dense network skeleton structure. The adhesion between the skeleton structure modified by the natural polyphenol compound and the para-aramid fiber is improved, and the phenolic hydroxyl groups in the natural polyphenol compound have a strong hydrogen bond adhesion effect with the polar hydrogenated nitrile rubber. The addition of butadiene-pyridine latex / carboxylated butadiene-nitrile latex to the system, followed by co-vulcanization with the rubber matrix, further improves the adhesion between the fiber and the rubber.

[0018] This invention improves the adhesion between para-aramid and hydrogenated nitrile rubber by adding carboxylated nitrile rubber latex with good bonding force to hydrogenated nitrile rubber and by proposing the optimal blending ratio of butyl pyridine latex and carboxylated nitrile rubber latex in a two-bath impregnation system. This ensures the reinforcing effect of para-aramid on hydrogenated nitrile rubber and helps to solve the problem of poor bonding force between para-aramid and hydrogenated nitrile rubber.

[0019] This invention incorporates a moisture-heat aging resistant agent into the impregnation solution. The addition of microencapsulated bisphenol A diglycidyl ether directly increases the cross-linking density of the interfacial phase, blocking water molecule penetration and reducing swelling and delamination of the interfacial phase. Rutile nano-TiO2 powder and nano-SiO2 powder are uniformly dispersed in the adhesive film, filling the micropores of the film, reducing the porosity of the interfacial layer, reducing the channels for water molecules to penetrate the bonding interface through the pores, and simultaneously improving the mechanical strength of the adhesive film, preventing brittleness and delamination under moisture and heat. Through the synergistic effect of chemical and physical methods, the moisture-heat aging resistance is improved.

[0020] The aramid impregnation line described in this invention has good adhesion to hydrogenated nitrile rubber, and also has advantages such as being green and environmentally friendly and resistant to damp heat aging, which is beneficial for the application of para-aramid / hydrogenated nitrile rubber composites in high-end fields such as aerospace. Attached Figure Description

[0021] Figure 1 This is a flowchart illustrating the preparation process of the aramid impregnation yarn of the present invention. Detailed Implementation

[0022] The specific embodiments of the present invention will be described in detail below. The present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed.

[0023] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used is for describing particular embodiments only and is not intended to limit the invention.

[0024] An aramid impregnation solution, the aramid impregnation solution comprising a one-bath impregnation solution and a two-bath impregnation solution; The one-bath impregnation solution comprises, by weight, 34-40 parts of anhydride-polyol copolymer, 17-20 parts of trimethylolpropane polyethylene ether, 12-15 parts of aminosilane coupling agent, 0.001-0.01 parts of glacial acetic acid, and 320-330 parts of deionized water. The two-bath impregnation solution comprises, by weight, 10-30 parts epoxy resin, 2-5 parts solubilizer, 3-9 parts natural polyphenol compound, 4-9 parts amine curing agent, 5-12 parts anti-damp heat aging agent, 180-250 parts deionized water, and 100-160 parts rubber latex.

[0025] Preferably, the two-bath impregnation solution comprises, by weight, 15 parts epoxy resin, 2-3 parts solubilizer, 4-5.5 parts natural polyphenol compound, 7-8 parts amine curing agent, 11 parts anti-humid heat aging agent, 240-245 parts deionized water, and 150 parts rubber latex.

[0026] Preferably, the weight ratio of the anhydride-polyol copolymer in the first bath impregnation solution to the epoxy resin in the second bath impregnation solution is (1.3-3.5):1.

[0027] More preferably, the weight ratio of the anhydride-polyol copolymer in the first bath impregnation solution to the epoxy resin in the second bath impregnation solution is (2.2-2.6):1.

[0028] Preferably, the weight ratio of the epoxy resin to the amine curing agent is (1.8-3.5):1.

[0029] Specifically, the anhydride-polyol copolymer is at least one of maleic anhydride-glycerol copolymer, maleic anhydride-pentaerythritol copolymer, and maleic anhydride-neopentyl glycol copolymer; The anhydride-polyol copolymers used in the embodiments of the present invention are selected from the following readily available copolymer product models involving polyols: CMA-2046 (BGI Chemical), T-1646 (BGI Chemical), MX-2325 (BGI Chemical), and MX-806 (BGI Chemical). However, these models do not constitute a limitation on the technical solution of the present invention.

[0030] The aminosilane coupling agent is at least one of KH792, KH540, and KH550.

[0031] Specifically, the epoxy resin is at least one of glycerol triglycidyl ether, neopentyl glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, propylene glycol diglycidyl ether, bisphenol A type epoxy resin, and bisphenol S type epoxy resin.

[0032] Specifically, the solubilizer is at least one of polyoxyethylene castor oil EL-40, propylene glycol methyl ether, and polyethylene glycol monomethyl ether; The natural polyphenolic compound is at least one of ellagitannin, gallic acid, ethyl gallate, and tannic acid; The amine curing agent is at least one of triethylenetetramine, dipropylenetriamine, cyclohexanetriamine, m-phenylenetriamine, isophorone-derived triamine, phenylcyclotriamine, and cyclohexanetetramine.

[0033] Specifically, the anti-damp heat aging aid is selected from at least one of microencapsulated bisphenol A diglycidyl ether, rutile nano TiO2 powder, and nano SiO2 powder; and the anti-damp heat aging aid includes at least microencapsulated bisphenol A diglycidyl ether.

[0034] Preferably, the anti-damp heat aging aid is a combination of microencapsulated bisphenol A diglycidyl ether and an inorganic anti-damp heat aging aid, wherein the inorganic anti-damp heat aging aid is selected from at least one of rutile nano TiO2 powder and nano SiO2 powder.

[0035] More preferably, the mass ratio of the natural polyphenol compound to the inorganic anti-damp heat aging agent is 1:(0.5-2.0). The mass ratio of the microencapsulated bisphenol A diglycidyl ether to the inorganic anti-damp heat aging agent is 1:(0.6-1.8).

[0036] Specifically, the rubber latex includes butadiene-pyridine latex and carboxylated butadiene-acrylonitrile latex, and the mass ratio of butadiene-pyridine latex to carboxylated butadiene-acrylonitrile latex is (3-7):1.

[0037] Specifically, the preparation method of the one-bath impregnation solution is as follows: Weigh 60-90 parts of deionized water according to the weight ratio and add it to the reaction vessel. While stirring at room temperature, add 5-12 parts of acid anhydride-polyol copolymer, 4-8 parts of trimethylolpropane polyethylene ether, 1-4 parts of aminosilane coupling agent, and 0.001-0.01 parts of glacial acetic acid to adjust the pH to 4-6. Stir for 5-15 minutes after each component is added to obtain a one-bath impregnation solution.

[0038] Specifically, the preparation method of the two-bath impregnation solution is as follows: According to the weight proportions, take 30-50 parts of deionized water, 10-30 parts of epoxy resin, 2-5 parts of solubilizer and 3-9 parts of natural polyphenol compound, stir and mix them, and react them at 40-80℃ and a stirring rate of 220 rpm-340 rpm for 20-40 minutes to obtain the intermediate product. The intermediate product is mixed with 4-9 parts of amine curing agent, 5-12 parts of anti-damp heat aging agent, 150-200 parts of deionized water and 100-160 parts of rubber latex, and cured for 6-12 hours to obtain a two-bath impregnation solution.

[0039] Preferably, the preparation method of the two-bath impregnation solution is as follows: According to the weight proportions, take 40-45 parts of deionized water, 15 parts of epoxy resin, 2-3 parts of solubilizer and 4-5.5 parts of natural polyphenol compound, stir and mix them, and react them at 40-80℃ and a stirring rate of 220 rpm-340 rpm for 20-40 min to obtain the intermediate product. The intermediate product is mixed with 7-8 parts of amine curing agent, 11 parts of anti-damp heat aging agent, 200 parts of deionized water and 150 parts of rubber latex, and then cured to obtain a two-bath impregnation solution.

[0040] A method for preparing aramid impregnated yarn, such as Figure 1 As shown, the preparation method is as follows: S1. After the twisted para-aramid fibers are immersed in a one-bath impregnation solution, they are sequentially sent to a one-bath drying system and a one-bath heat treatment system for dehydration, drying and heat treatment. S2. The para-aramid fiber treated in step S1 is impregnated in a second bath impregnation solution, and then sequentially enters a second bath drying system and a second bath heat treatment system for dehydration, drying and heat treatment to obtain aramid impregnated line. The one-bath impregnation solution is the one-bath impregnation solution of the present invention; The two-bath impregnation solution is the two-bath impregnation solution described in this invention.

[0041] Specifically, in step S1, the twisted para-aramid fibers are impregnated in a bath at a traction speed of 2-8 m / min for 30-80 s, then dried at 100-130 ℃ for 60-120 s, and finally drawn to a heat treatment system for heat treatment at 170-210 ℃ for 60-120 s. In step S2, the twisted para-aramid fibers are impregnated in a second bath impregnation solution at a traction speed of 2-8 m / min for 30-80 s, then dried at 100-130 ℃ for 60-120 s, and finally drawn into a heat treatment system for heat treatment at 210-230 ℃ for 60-150 s to obtain aramid impregnated yarn.

[0042] The twisted para-aramid fiber used in this embodiment of the invention is: 1000D (fineness of a single twisted fiber), 1×3 (yarn structure), S / Z (twisting direction of primary / secondary twist), 225 / 130 (twisting degree of primary / secondary twist).

[0043] The present invention also discloses an aramid impregnated yarn, which is prepared by the preparation method described in the present invention.

[0044] Example 1 The preparation process of an aramid impregnated yarn is as follows: Preparation of one-bath impregnation solution: Weigh 330 g of deionized water and add it to the reaction vessel. Under stirring at room temperature, add 36 g of MX-2325, 18 g of trimethylolpropane polyethylene ether (TMP-3EO, Huangma New Materials), 6.5 g of KH550, 6.5 g of KH540 and 0.01 g of glacial acetic acid to adjust the pH to 4. Stir for 8 min after each component is added to obtain the one-bath impregnation solution. One-bath impregnation: The twisted para-aramid fibers are impregnated through a process such as... Figure 1 The fiber impregnation device shown impregnates the fiber in a one-bath impregnation tank at a traction speed of 5 m / min for 60 s, then dries it at 115℃ for 90 s, and finally tractions it to the heat treatment system for heat treatment at 200℃ for 120 s. Preparation of the two-bath impregnation solution: 40 g of deionized water, 15 g of 1,4-butanediol diglycidyl ether (D070131, Anaiji), 2.2 g of propylene glycol methyl ether, and 4 g of gallic acid were mixed and stirred. The mixture was then reacted at 70 °C with a stirring rate of 280 rpm for 25 min to obtain an intermediate product. The obtained intermediate product was mixed with 8 g of triethylenetetramine, 3 g of rutile nano-TiO2 powder, 5 g of microencapsulated bisphenol A diglycidyl ether (Yingxing New Materials), 3 g of nano-SiO2, 200 g of deionized water, 120 g of butadiene-pyridine latex (TC-P601, Tianchen Adhesive Industry), and 30 g of carboxylated butadiene-acrylonitrile latex (Bense, Jingbang Polymer) and matured for 8 h to obtain the two-bath impregnation solution. Second bath impregnation: The para-aramid fibers that have been impregnated in the first bath are impregnated in the second bath impregnation tank at a traction speed of 5 m / min for 60 s, then dried at 110 ℃ for 90 s, and finally drawn to the heat treatment system and heat treated at 220 ℃ for 120 s to obtain aramid impregnated yarn.

[0045] Example 2 The preparation process of an aramid impregnated yarn is as follows: Preparation of one-bath impregnation solution: Weigh 320 g of deionized water and add it to the reaction vessel. Under stirring at room temperature, add 34 g of CMA-2046 (Huada Chemical), 17 g of trimethylolpropane polyethylene ether (TMP-3EO, Huangma New Materials), 14 g of KH792 and 0.01 g of glacial acetic acid to adjust the pH to 4. Stir for 12 min after each component is added to obtain the one-bath impregnation solution. One-bath impregnation: The twisted para-aramid fibers are impregnated through a process such as... Figure 1 The fiber impregnation device shown impregnates the fiber in a one-bath impregnation tank at a traction speed of 4 m / min for 75 s, then dries it for 112 s at 105℃, and finally tractions it to the heat treatment system for heat treatment at 190℃ for 150 s. Preparation of the two-bath impregnation solution: 40 g of deionized water, 15 g of neopentyl glycol diglycidyl ether (D070034, Anaiji), 3 g of polyoxyethylene castor oil EL-40, and 5 g of ellagitannin (Chicheng Biotechnology) were mixed and stirred. The mixture was then reacted at 60 ℃ and a stirring rate of 280 rpm for 30 min to obtain an intermediate product. The obtained intermediate product was mixed with 8 g of m-phenylenediamine, 4 g of rutile nano-TiO2 powder, 4 g of microencapsulated bisphenol A diglycidyl ether (Yingxing New Materials), 3 g of nano-SiO2, 200 g of deionized water, 125 g of butadiene-pyridine latex (TC-P601, Tianchen Adhesive Industry), and 25 g of carboxylated butadiene-acrylonitrile latex (Bense, Jingbang Polymer) and matured for 10 h to obtain the two-bath impregnation solution. Two-bath impregnation: The para-aramid fibers treated with the first-bath impregnation are impregnated in the second-bath impregnation tank at a traction speed of 4 m / min for 75 s, then dried at 100 ℃ for 115 s, and finally drawn to the heat treatment system and heat-treated at 210 ℃ for 150 s to obtain the aramid impregnated yarn.

[0046] Example 3 The preparation process of an aramid impregnated yarn is as follows: Preparation of one-bath impregnation solution: Weigh 330 g of deionized water and add it to the reaction vessel. Under stirring at room temperature, add 39 g of T-1646 (Huada Chemical), 19 g of trimethylolpropane polyethylene ether (TMP-3EO, Huangma New Materials), 13 g of KH540 and 0.01 g of glacial acetic acid to adjust the pH to 4. Stir for 6 min after each component is added to obtain the one-bath impregnation solution. One-bath impregnation: The twisted para-aramid fibers are impregnated through a process such as... Figure 1 The fiber impregnation device shown impregnates the fiber in a one-bath impregnation tank at a traction speed of 5 m / min for 60 s, then dries it at 115℃ for 90 s, and finally tractions it to the heat treatment system for heat treatment at 200℃ for 120 s. Preparation of the two-bath impregnation solution: 45 g of deionized water, 15 g of glycerol triglycidyl ether (G885937, Maclean), 2.2 g of polyethylene glycol monomethyl ether (Jinyueyuan New Materials), and 5.5 g of tannic acid were mixed and stirred. The mixture was then reacted at 75 ℃ and a stirring rate of 280 rpm for 25 min to obtain an intermediate product. The obtained intermediate product was mixed with 7 g of dipropylenetriamine, 5 g of rutile nano-TiO2 powder, 6 g of microencapsulated bisphenol A diglycidyl ether (Yingxing New Materials), 200 g of deionized water, 130 g of butadiene-pyridine latex (TC-P601, Tianchen Adhesive Industry), and 20 g of carboxylated butadiene-acrylonitrile latex (Bense, Jingbang Polymer), and matured for 9 h to obtain the two-bath impregnation solution. Two-bath impregnation: The para-aramid fibers treated with the first-bath impregnation are impregnated in the second-bath impregnation tank at a traction speed of 5 m / min for 60 s, then dried at 110 ℃ for 90 s, and finally drawn to the heat treatment system and heat-treated at 220 ℃ for 120 s to obtain the aramid impregnated yarn.

[0047] Example 4 The preparation process of an aramid impregnated yarn is as follows: Preparation of one-bath impregnation solution: Weigh 320 g of deionized water and add it to the reaction vessel. Under stirring at room temperature, add 34 g of MX-806 (Huada Chemical), 17 g of trimethylolpropane polyethylene ether (TMP-3EO, Huangma New Materials), 13 g of KH550 and 0.01 g of glacial acetic acid to adjust the pH to 4. Stir for 5 min after each component is added to obtain the one-bath impregnation solution. One-bath impregnation: The twisted para-aramid fibers are impregnated through a process such as... Figure 1 The fiber impregnation device shown impregnates the fiber in a one-bath impregnation tank at a traction speed of 4 m / min for 75 s, then dries it for 112 s at 105℃, and finally tractions it to the heat treatment system for heat treatment at 190℃ for 150 s. Preparation of the two-bath impregnation solution: 40 g of deionized water, 15 g of bisphenol A type epoxy resin (E-51, Maclean), 3 g of propylene glycol methyl ether, and 5 g of ethyl gallate were mixed and stirred. The mixture was then reacted at 60 °C and a stirring rate of 280 rpm for 30 min to obtain an intermediate product. The obtained intermediate product was mixed with 8 g of cyclohexanetriamine, 5 g of microencapsulated bisphenol A diglycidyl ether (Yingxing New Materials), 6 g of nano-SiO2, 200 g of deionized water, 115 g of butadiene-pyridine latex (TC-P601, Tianchen Adhesive Industry), and 35 g of carboxylated butadiene-acrylonitrile latex (Bense, Jingbang Polymer) and matured for 12 h to obtain the two-bath impregnation solution. Two-bath impregnation: The para-aramid fibers treated with the first-bath impregnation are impregnated in the second-bath impregnation tank at a traction speed of 4 m / min for 75 s, then dried at 100 ℃ for 115 s, and finally drawn to the heat treatment system and heat-treated at 210 ℃ for 150 s to obtain the aramid impregnated yarn.

[0048] Example 5 The preparation process of an aramid impregnated yarn is as follows: Preparation of one-bath impregnation solution: Weigh 320 g of deionized water and add it to the reaction vessel. Under stirring at room temperature, add 34 g of CMA-2046 (Huada Chemical), 17 g of trimethylolpropane polyethylene ether (TMP-3EO, Huangma New Materials), 13 g of KH550 and 0.01 g of glacial acetic acid to adjust the pH to 4. Stir for 5 min after each component is added to obtain the one-bath impregnation solution. One-bath impregnation: The twisted para-aramid fibers are impregnated through a process such as... Figure 1 The fiber impregnation device shown impregnates the fiber in a one-bath impregnation tank at a traction speed of 4 m / min for 75 s, then dries it for 112 s at 105℃, and finally tractions it to the heat treatment system for heat treatment at 190℃ for 150 s. Preparation of the two-bath impregnation solution: 30 g of deionized water, 10 g of bisphenol S-type epoxy resin (DMH-602, Maidehao Chemical), 2 g of propylene glycol methyl ether, and 3 g of gallic acid were mixed and stirred. The mixture was then reacted at 80 ℃ and a stirring rate of 220 rpm for 40 min to obtain an intermediate product. The obtained intermediate product was mixed with 4 g of cyclohexanetriamine, 3 g of microencapsulated bisphenol A diglycidyl ether (Yingxing New Materials), 2 g of nano-SiO2, 150 g of deionized water, 75 g of butadiene-pyridine latex (TC-P601, Tianchen Adhesive Industry), and 25 g of carboxylated butadiene-acrylonitrile latex (Bense, Jingbang Polymer) and matured for 12 h to obtain the two-bath impregnation solution. Two-bath impregnation: The para-aramid fibers treated with the first-bath impregnation are impregnated in the second-bath impregnation tank at a traction speed of 4 m / min for 75 s, then dried at 100 ℃ for 115 s, and finally drawn to the heat treatment system and heat-treated at 210 ℃ for 150 s to obtain the aramid impregnated yarn.

[0049] Example 6 The preparation process of an aramid impregnated yarn is as follows: Preparation of one-bath impregnation solution: Weigh 330 g of deionized water and add it to the reaction vessel. Under stirring at room temperature, add 40 g of MX-2325, 20 g of trimethylolpropane polyethylene ether (TMP-3EO, Huangma New Materials), 15 g of KH550 and 0.01 g of glacial acetic acid to adjust the pH to 4. Stir for 5 min after each component is added to obtain the one-bath impregnation solution. One-bath impregnation: The twisted para-aramid fibers are impregnated through a process such as... Figure 1 The fiber impregnation device shown impregnates the fiber in a one-bath impregnation tank at a traction speed of 4 m / min for 75 s, then dries it for 112 s at 105℃, and finally tractions it to the heat treatment system for heat treatment at 200℃ for 100 s. Preparation of the two-bath impregnation solution: 50 g of deionized water, 30 g of bisphenol A type epoxy resin (E-51, Maclean), 5 g of propylene glycol methyl ether, and 9 g of tannic acid were mixed and stirred. The mixture was then reacted at 40 ℃ and a stirring rate of 340 rpm for 40 min to obtain an intermediate product. The obtained intermediate product was then mixed with 9 g of cyclohexanetriamine, 7 g of microencapsulated bisphenol A diglycidyl ether (Yingxing New Materials), 5 g of nano-SiO2, 200 g of deionized water, 140 g of butadiene-pyridine latex (TC-P601, Tianchen Adhesive Industry), and 20 g of carboxylated butadiene-acrylonitrile latex (Bense, Jingbang Polymer) and matured for 12 h to obtain the two-bath impregnation solution. Two-bath impregnation: The para-aramid treated in the first bath is impregnated in the second bath impregnation tank at a traction speed of 4 m / min for 75 s, then dried at 100 ℃ for 115 s, and finally drawn to the heat treatment system and heat treated at 230 ℃ for 120 s to obtain the aramid impregnated thread.

[0050] Comparative Example 1 The cleaned and dried para-aramid twisted fibers were directly compounded with hydrogenated nitrile butadiene rubber to prepare fiber-reinforced rubber composites.

[0051] Comparative Example 2 Aramid impregnated yarns were prepared using the same method as in Example 1, except that no anti-damp heat aging additives (i.e., no rutile nano TiO2 powder, microencapsulated bisphenol A diglycidyl ether, or nano SiO2) were added to the two-bath impregnation solution of Comparative Example 1.

[0052] Comparative Example 3 Aramid impregnated yarns were prepared using the same method as in Example 1, except that: microencapsulated bisphenol A diglycidyl ether was not added to the two-bath impregnation solution of Comparative Example 3, only an inorganic anti-damp heat aging agent was added.

[0053] Comparative Example 4 Aramid impregnated yarns were prepared using the same method as in Example 1, except that trimethylolpropane polyethylene ether was not added to the one-bath impregnation solution of Comparative Example 4.

[0054] Comparative Example 5 Aramid impregnated yarn was prepared using the same method as in Example 1, except that the amount of natural polyphenol compound used in Comparative Example 5 was reduced, i.e., the amount of gallic acid added was 2 g, so that the mass ratio of natural polyphenol compound to inorganic anti-damp heat aging agent was 1:3.

[0055] Comparative Example 6 Aramid impregnated yarns were prepared using the same method as in Example 1, except that the amount of microencapsulated bisphenol A diglycidyl ether added was reduced (1 g), while the amount of inorganic anti-damp heat aging agent added was increased (5 g rutile nano-TiO2 powder, 5 g nano-SiO2). This resulted in a mass ratio of microencapsulated bisphenol A diglycidyl ether to inorganic anti-damp heat aging agent of 1:10.

[0056] Comparative Example 7 Aramid impregnated yarns were prepared using the same method as in Example 1, except that the amount of anhydride-polyol copolymer added in the first bath impregnation solution was reduced in Comparative Example 7. Specifically, the amount of maleic anhydride-glycerol copolymer added in Comparative Example 7 was 15 g (the weight ratio of the anhydride-polyol copolymer in the first bath impregnation solution to the epoxy resin in the second bath impregnation solution was 1:1).

[0057] Using hydrogenated nitrile butadiene rubber compound, according to GB / T2942-2009 "Determination of Static Adhesion Strength between Vulcanized Rubber and Fiber Cord - H Extraction Method", adhesive samples were prepared and adhesive properties were tested for the fibers of Examples 1-6 and Comparative Examples 1-7. The hydrogenated nitrile butadiene rubber compound was HNBR-YC80 (Huami New Materials).

[0058] Extraction Test Instructions: The extraction test of the adhesion between para-aramid and rubber was conducted according to GB / T2942-2009 standard on an electronic tensile testing machine manufactured by INSTRON, UK, at a test speed of 130 mm / min. The maximum force when the fiber was pulled out of the rubber was recorded. At least 10 samples were tested, and the average of at least 10 valid data points was recorded. Peel Test Instructions: The peel test of the adhesion was conducted according to GB / T 40725-2021 standard on an electronic tensile testing machine at a test speed of 300 mm / min. The maximum force when the fiber was peeled from the rubber at 180° was recorded. At least 6 samples were tested, and the average of at least 6 valid data points was recorded. A double 85 constant temperature and humidity chamber was used. The tensile specimens were subjected to damp heat aging treatment at 85 ℃±0.5 ℃ and 85 % RH±2 %RH for 72 h, followed by extraction and peel tests after damp heat aging. The specific test results are shown in Table 1 below.

[0059] Table 1 Performance Test Results

[0060] Remark: (1) The specific calculation method for the H-pulling force retention rate of the sample after damp heat aging is as follows: (Where, σ1 - the H-pulling force of the sample before damp heat aging, N; σ2 - the H-pulling force of the sample after damp heat aging, N); the specific calculation method for the 180° peel force retention rate of the sample after damp heat aging is as follows: (In the formula, λ1-peeling force of the sample before damp heat aging, N; λ2-peeling force of the sample after damp heat aging, N).

[0061] (2) In the comparative analysis of the following examples and comparative examples, the decrease in extraction force of the comparative examples before wet heat aging was analyzed and calculated using the following formula: (Where, σ3 - pull-out force H of the example sample before damp heat aging, N; σ4 - pull-out force H of the comparative example sample before damp heat aging, N); the decrease in peel force of the comparative example before damp heat aging was analyzed and calculated using the following formula: (In the formula, λ3 - peel force of the example sample before damp heat aging, N; λ4 - peel force of the comparative sample before damp heat aging, N).

[0062] (3) In the comparative analysis of the following examples and comparative examples, the decrease in the extraction force retention rate of the comparative examples after wet heat aging was analyzed and calculated using the following formula: (Where, υ1 - the retention rate of the pullout force of sample H after damp heat aging in the example, %; υ2 - the retention rate of the pullout force of sample H after damp heat aging in the comparative example, %); the decrease in the peel force retention rate of the comparative example after damp heat aging compared to the example was calculated using the following formula: (In the formula, ω 1-Retention rate of the H-pulse force of the sample after damp heat aging in Example 1, % ω 2-Comparative sample H extraction force retention rate after damp heat aging, %).

[0063] The results in the table above show that Examples 1-6 utilize the formaldehyde-free, non-toxic, and non-organic solvent-free water-soluble impregnation system of this invention. Through two-bath impregnation modification, the interfacial adhesion between para-aramid and hydrogenated nitrile butadiene rubber is improved. Simultaneously, a moisture barrier is constructed using anti-damp heat aging additives, thereby enhancing the composite material's resistance to damp heat aging. Compared to Comparative Example 1 without surface modification of the aramid, the H-pull-out force and 180° peel force with hydrogenated nitrile butadiene rubber are increased by at least 140%. The test results demonstrate that the aramid impregnation solution prepared in this application can significantly improve the adhesion between para-aramid and hydrogenated nitrile butadiene rubber.

[0064] By comparing the H-pull force and 180° peel data after 72 h of damp heat aging of Comparative Example 2 and Example 1, it can be seen that, compared with Example 1, the pull force retention rate of Comparative Example 2 decreased by 31.02% and the peel force retention rate decreased by 31.99% after damp heat aging. The adhesive force retention rate of Comparative Example 2 was even lower after damp heat aging, which proves that the para-aramid fiber treated with the anti-damp heat aging agent impregnation solution has stronger damp heat aging resistance after being combined with hydrogenated nitrile rubber.

[0065] A comparison of the experimental results of Comparative Example 3 and Example 1 shows that if microencapsulated bisphenol A diglycidyl ether is not added to the two-bath impregnation solution, and only an inorganic anti-moisture-heat aging aid is added, the poor compatibility between the single inorganic filler component and the phase interface will lead to a 35.38% decrease in pull-out force before moisture-heat aging, a 50.85% decrease in peel force before moisture-heat aging, a 30.5% decrease in pull-out force retention rate after moisture-heat aging, and a 24.86% decrease in peel force retention rate after moisture-heat aging. Microencapsulated bisphenol A diglycidyl ether slowly ruptures during heat treatment, releasing epoxy groups that can react with the active functional groups such as hydroxyl and carboxyl groups introduced by the one-bath impregnation solution, and undergo secondary cross-linking with the amino and hydroxyl groups in the two-bath cross-linking network. This increases the cross-linking density of the interfacial phase, offsetting the cross-linking network defects that may be caused by the inorganic powder, thereby improving adhesion.

[0066] A comparison of the experimental results of Comparative Example 4 and Example 1 shows that if trimethylolpropane polyethylene ether is not added to the first-bath impregnation solution, insufficient impregnation and poor interfacial layer density will result in a 40.28% decrease in pull-out force before wet heat aging, a 53.27% decrease in peel force before wet heat aging, a 23.0% decrease in pull-out force retention rate after wet heat aging, and a 13.64% decrease in peel force retention rate after wet heat aging. The addition of trimethylolpropane polyethylene ether reduces the surface tension of the aramid after the first-bath impregnation, allowing the second-bath impregnation solution to fully impregnate the aramid, ensuring the density of the cross-linked layer in the second bath, thereby improving the bonding performance between the aramid impregnation line and the hydrogenated nitrile rubber compound.

[0067] A comparison of the experimental results of Comparative Example 5 and Example 1 shows that reducing the amount of natural polyphenol compound leads to a 30.4% decrease in pull-out force before wet heat aging, a 43.96% decrease in peel force before wet heat aging, a 29.28% decrease in pull-out force retention rate after wet heat aging, and a 16.36% decrease in peel force retention rate after wet heat aging. Because the inorganic anti-wet heat aging additive is a rigid inorganic powder, its addition will harden and embrittle the cross-linking network. The natural polyphenol compound undergoes a ring-opening reaction with the epoxy groups, introducing flexible phenolic hydroxyl segments into the cross-linking skeleton, counteracting the rigidification tendency brought about by the inorganic powder and ensuring adhesion. Therefore, the combination of the amount of natural polyphenol compound added and the inorganic anti-wet heat aging additive is more conducive to obtaining a para-aramid / hydrogenated nitrile rubber composite material with excellent comprehensive performance.

[0068] A comparison of the experimental results of Comparative Example 6 and Example 1 shows that if the amount of microencapsulated bisphenol A diglycidyl ether added is reduced and the amount of inorganic anti-moisture-heat aging agent added is increased, the pull-out force before moist-heat aging will decrease by 33.46%, the peel force before moist-heat aging will decrease by 48.51%, the pull-out force retention rate after moist-heat aging will decrease by 14.47%, and the peel force retention rate after moist-heat aging will decrease by 19.46%.

[0069] A comparison of the experimental results of Comparative Example 7 and Example 1 shows that reducing the amount of anhydride-polyol copolymer added to the first-bath impregnation solution leads to a 43.02% decrease in pull-out force before wet heat aging, a 55.61% decrease in peel force before wet heat aging, a 16.15% decrease in pull-out force retention rate after wet heat aging, and a 14.88% decrease in peel force retention rate after wet heat aging due to the poor activation effect of the first bath on the fiber surface. This is because the anhydride-polyol copolymer can introduce polar functional groups such as carboxyl and hydroxyl groups onto the surface of aramid fibers. These functional groups can undergo ring-opening reactions with the epoxy groups in the epoxy resin of the second-bath impregnation solution, achieving chemical bonding between the crosslinked skeleton of the second bath and the aramid surface, thereby improving the adhesion performance between aramid fibers and hydrogenated nitrile rubber.

[0070] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are exhaustively listed. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0071] For those skilled in the art, various modifications and improvements can be made without departing from the concept of the present invention, and these all fall within the scope of protection of the present invention. The scope of protection of the present invention is defined by the appended claims.

Claims

1. An aramid impregnation solution, characterized in that, The aramid impregnation solution includes a one-bath impregnation solution and a two-bath impregnation solution; The one-bath impregnation solution comprises, by weight, 34-40 parts of anhydride-polyol copolymer, 17-20 parts of trimethylolpropane polyethylene ether, 12-15 parts of aminosilane coupling agent, 0.001-0.01 parts of glacial acetic acid, and 320-330 parts of deionized water. The two-bath impregnation solution comprises, by weight, 10-30 parts epoxy resin, 2-5 parts solubilizer, 3-9 parts natural polyphenol compound, 4-9 parts amine curing agent, 5-12 parts anti-damp heat aging agent, 180-250 parts deionized water, and 100-160 parts rubber latex.

2. The aramid impregnation solution according to claim 1, characterized in that, The anhydride-polyol copolymer is at least one of maleic anhydride-glycerol copolymer, maleic anhydride-pentaerythritol copolymer, and maleic anhydride-neopentyl glycol copolymer; The aminosilane coupling agent is at least one of KH792, KH540, and KH550.

3. The aramid impregnation solution according to claim 1, characterized in that, The epoxy resin is at least one of glycerol triglycidyl ether, neopentyl glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, bisphenol A type epoxy resin, and bisphenol S type epoxy resin.

4. The aramid impregnation solution according to claim 1, characterized in that, The solubilizer is at least one of polyoxyethylene castor oil EL-40, propylene glycol methyl ether, and polyethylene glycol monomethyl ether. The natural polyphenolic compound is at least one of ellagitannin, gallic acid, ethyl gallate, and tannic acid; The amine curing agent is at least one of triethylenetetramine, dipropylenetriamine, cyclohexanetriamine, m-phenylenetriamine, isophorone-derived triamine, phenylcyclotriamine, and cyclohexanetetramine.

5. The aramid impregnation solution according to claim 1, characterized in that, The anti-damp heat aging aid is selected from at least one of microencapsulated bisphenol A diglycidyl ether, rutile nano TiO2 powder, and nano SiO2 powder; and the anti-damp heat aging aid includes at least microencapsulated bisphenol A diglycidyl ether.

6. The aramid impregnation solution according to claim 1, characterized in that, The rubber latex includes butadiene-pyridine latex and carboxylated butadiene-acrylonitrile latex, and the mass ratio of butadiene-pyridine latex to carboxylated butadiene-acrylonitrile latex is (3-7):

1.

7. The aramid impregnation solution according to claim 1, characterized in that, The preparation method of the two-bath impregnation solution is as follows: According to the weight proportions, take 30-50 parts of deionized water, 10-30 parts of epoxy resin, 2-5 parts of solubilizer and 3-9 parts of natural polyphenol compound, stir and mix them, and then react them under stirring conditions at 40-80℃ to obtain intermediate products. The intermediate product is mixed with 4-9 parts of amine curing agent, 5-12 parts of anti-damp heat aging agent, 150-200 parts of deionized water and 100-160 parts of rubber latex, and then cured to obtain a two-bath impregnation solution.

8. A method for preparing aramid impregnated yarn, characterized in that, The preparation method is as follows: S1. After the twisted para-aramid fibers are immersed in a one-bath impregnation solution, they are dehydrated, dried, and heat-treated. S2. The para-aramid fiber treated in step S1 is impregnated in a second bath impregnation solution, and then dried and heat-treated to obtain aramid impregnated yarn. The one-bath impregnation solution is the one-bath impregnation solution according to any one of claims 1-7; The two-bath impregnation solution is the two-bath impregnation solution described in any one of claims 1-7.

9. The method for preparing an aramid impregnated yarn according to claim 8, characterized in that, In step S1, the twisted para-aramid fibers are impregnated in a bath at a traction speed of 2-8 m / min for 30-80 s, then dried at 100-130 ℃ for 60-120 s, and finally drawn to a heat treatment system for heat treatment at 170-210 ℃ for 60-120 s. In step S2, the twisted para-aramid fibers are impregnated in a second-bath impregnation solution at a traction speed of 2-8 m / min for 30-80 s, then dried at 100-130 ℃ for 60-120 s, and finally drawn into a heat treatment system for heat treatment at 210-230 ℃ for 60-150 s to obtain aramid impregnated yarn.

10. An aramid impregnated yarn, characterized in that, The aramid impregnated thread is prepared by the preparation method described in any one of claims 8-9.

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